Transverse hydrostatic upp drive

ABSTRACT

A unitary power package having an engine, a pump and motor hydrostatic transmission and a differential. The engine housing has an annular transmission mounting pad about the engine drive shaft and a differential housing portion. The hydrostatic transmission housing has an intermediate wall portion having on one side a cylindrical pump portion and the motor power passage portion on a motor axis and on the other side a pump power passage portion on the pump axis and a motor cylindrical portion on the motor axis. The pump and motor cylindrical portions partially overlap. The connecting power passage portions from the pump power passages follow the motor cylindrical portion, cross the intermediate wall at the nape between the cylindrical portions and then follow the pump cylindrical portions to the motor power passages. The motor shaft extends through the motor pintle to drive the differential in the differential housing portion of the engine housing.

United States Patent [191 Hause TRANSVERSE HYDROSTATIC UPP DRIVE [75]Inventor: Gilbert K. Hause, Bloomfield Hill Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[221 Filed: May 4, 1972 [21] Appl. No.: 250,368

[52] U.S. Cl 74/701, 74/695, 74/687, 74/731 [51] Int. Cl. F16k 37/08,Fl6k 47/04, Fl6k 47/00 [58] Field of Search 74/701, 695

[56] References Cited UNITED STATES PATENTS 2,123,005 7/l938 Ford 74/701X 3,029,662 4/1962 Hause 74/695 3,453,904 7/1969 Dangauthier 74/701 X3,473,413 10/1969 Stockton..... 74/695 3,578,760 5/1971 Shinmura...74/70l 3,703,107 11/1972 Piret 74/695 FOREIGN PATENTS OR APPLICATIONS1,159,280 12/1963 Germany 74/701 Apr. 23, 1974 Primary Examiner-ArthurT. McKeon Attorney, Agent, or FirmA. M. I-Ieiter [5 7] ABSTRACT Aunitary power package having an engine, a pump and motor hydrostatictransmission and a differential. The engine housing has an annulartransmission mounting pad about the engine drive shaft and adifferential housing portion. The hydrostatic transmission housing hasan intermediate wall portion having on one side a cylindrical pumpportion and the motor power passage portion on a motor axis and on theother side a pump power passage portion on the pump axis and a motorcylindrical portion on the motor axis. The pump and motor cylindricalportions partially overlap. The connecting power passage portions fromthe pump power passages follow the motor cylindrical portion, cross theintermediate wall at the nape between the cylindrical portions and thenfollow the pump cylindrical portions to the motor power passages. Themotor shaft extends through the motor pintle to drive the differentialin the differential housing portion of the engine housing.

6 Claims, 3 Drawing Figures PATENTEBAPR 23 F974 SHEET 2 [IF 2 1TR-ANSVERSE HYDROSTATIC UPP DRIVE This invention relates to hydrostatictransmissions and particularly a unitary power package hydrostatictransmission drive.

This invention provides a rigid, lightweight, and compact pump motorhydrostatic transmission having a housing consisting of three basicmembers, a main housing wall providing both the pump and motor supportand chamber enclosing portions and a pump coverplate and a motorcoverplate covering the respective chambers. In the main housing partthe cylindrical pump and motor housing portions are located in partiallyoverlapping relation on opposite sides of the intermediate wall. Thepower passages connecting the pump and motor are formed as a portion ofthe main housing wall port. These power passages have a pump passageportion at the pump ports on the side of the intermediate wall oppositethe pump chamber and a motor passage portion at the motor ports on theside of the intermediate wall opposite the motor. These pump and motorpassage portions are thus respectively adjacent and have common portionsrespectively with the cylindrical motor and pump housing portions. Thepower passagesalso have connecting portions which extend from the pumppassage portions along the perimeter of the motor cylindrical housingportion to the nape between the cylindrical housing portions, Where theycross over the intermediate wall and extend along the perimeter of thepump cylindrical housing portion to the motor passage portion.

In this integral cast arrangement, the intermediate wall, cylindricalhousing portions and passage portions are strengthened by each other.The cylindrical housing portions and the passage portions, which providethe housing the passage structure, act as strengthening ribs. Thecylindrical pump and motor housing portions are partially overlapped sothey are adjacent the motor and pump ports respectively and have commonwall portions with the motor and pump passage portions to minimize theoffset distance between the pump and motor axes, reduce the length ofthe power passages bly.

In the power package assembly, the cylindrical pump housing portion issecured to the annular mounting pad on the engine housing located aroundthe engine drive shaft and follows the pump cylindrical wall and motorpassage portion. The engine drive shaft is connected to the pump shaft.The motor output shaft extends from the motor housing portion in thesame direction as the pump shaft and to a differential drive gearlocated in a differential housing portion of the engine housing. Thedifferential drive gear is connected by a chain to the differential ringgear to drive the differential. The swing axle differential has acarrier with an internal cylindrical bearing, having cylindrical bevelgears with through opposite axial slots receiving the universal balldrive members rotatably mounted on a pin fixed in the inboard end ofeach swing axle. I

These and other features of the invention will be more apparent from thefollowing description and drawings.

FIG. 1 is an elevation view of the power package with parts in sectionto show details.

FIG. 2 is a section of FIG. 1 on the line 2-2.

and provide a compact hydrostatic transmission assem- FIG. 3schematically shows a modified differential arrangement.

Referring to the drawing, the power package or assembly consists of anengine 10, a hydrostatic transmission assembly 1 1 and a finaldifferential drive assembly 12. While any conventional engine may beused, a V-8 engine is shown having an engine block 14, a head 15, alower housing or oil pan l6 and a valve cover 17 conventionally securedtogether to provide an engine housing 18. The V-8 type internalcombustion engine 10 has conventional power generating means,illustrated in part by the crankshaft l9 and cylinders 20 shown indotted lines. The output shaft 21, a portion of the crankshaft 19, isrotatably supported in bearings 22 and sealed by seal 23 in the end wall24 of the engine housing 18 and the axis 25. The end wall 24 has asuitable securing flange and pad 30 to support the hydrostatictransmission 11, as explained in more detail below. A flywheel 26 issecured by screws 27 to the flange 28 on shaft 21. A conventional springdamper 29 is suitably secured by screws 31 to the flywheel and haslocated in a bore in shaft 21, an internal splined hub 32 driving thehydrostatic transmission input shaft or pump drive shaft 33.

The hydrostatic transmission assembly 11 has a main housing portion 36common to both of the pump and motor units and a circular pump coverplate portion 37 and a motor cover plate portion 38 respectively securedthereto by a suitable annular series of screws 39 and 41 respectively.The main housing portion 36 has a central or intermediate wall portion42 which has integrally formed therewith, on the inboard side, acylindrical pump housing portion 43and a central pintle support portion44 both located concentrically about the engine and the pump axis 25 anda central axial motor passage portion 46 concentric with the motor axis47 which is parallel to, but offset from, the pump axis 25. On theother, or outboard, side of the intermediate wall 42, there is alsointegrally formed the cylindrical motor portion 48 and the central motorpintle support portion 49, both concentric to the motor axis 47 and thecentral pump axial passage portion 51.

The pumps and motors are of a conventional piston and cylinder type, forexample, the radial piston pump shown in the BE. Simmons U.S. Pat. No.3,274,946 issued Sept. 27, l966JThe pump has a cylindrical pintle 52having a flange secured by suitable screws 53 to the pump pintle supportportion 44 of the housing central wall portion 42. Pintle 52 has anexternal cylindrical bearing in the internal cylindrical bearing of thespider 54 to rotatably support the spider. The spider has radialspherical pistons 56 cooperating with radial cylinders 57 which have aslipper base slidably mounted on the bearing ring 58. The bearing ringis rotatably supported on needle bearings 59 in the internal bearingsurface of the bearing support 61 which is mounted at each side forreciprocable displacement varying movement on the bearing blocks 63secured by screws 64 to the intermediate wall portion 42 and moved by asuitable piston and cylinder displacement control actuator or servomotor 65. This pump displacement varying means, by moving the supportring, variably moves the center of the pump bearing ring to either sideof the center of the pump pintle and spider or pump axis to variablypump fluid in either direction for forward or reverse drive when themotor variable displacement means variably maintains the motor bearingring on 3 one side'of the motor axis. This displacement varying means isdescribed and shown in more detail in connection with the followingdescription of the motor. The pump pintle 52 has a first pintle passage66 and a second pintle passage 67 connected respectively to the first 68and second 69 axial passage portion in the axial passage portion 51 ofintermediate wall 42. These passages are a part of the power circuitpassages connecting the pump-to the motor to hydrostatically deliverpower. One of these passages is a supply or high pressure passage andthe other a return or low pressure passage depending on the direction ofmotor rotation, the position of the variable displacement control andwhether the transmission is functioning to drive the output or theoutput is driving, as during overrun brakmg.

The pump shaft 33, which is driven by the splined connection with thehub 32 of damper 29, is connected by suitable fasteners, i.e., rivets 71to drive the spider 54 and passes through a seal and aperture 72 in thepump cover plate 37.

The motor 76 is similarly constructed and has a pintle 77 having aflange similarly secured by screws 75 to the motor pintle supportportion 49 of the intermediate wall 42. The motor spider 78 has acylindrical internal bearing surface mounted on the cylindrical externalbearing surfaceof the pintle for rotation thereon and radial sphericalpistons 79 which reciprocate in the radial cylinders 81 which have aslipper base slidably mounted on the internal cylindrical bearingsurface of bearing support 82; The bearing ring 82 is rotatably mountedby needle bearings83 on the internal cylindrical bearing surface of thebearing support 84 which is reciprocably mounted on oppositely disposedbearing blocks 86 secured by screws 87 to the intermediate wall. Thebearing support has opposite parallel bearing surfaces in bearingengagement with'similar surfaces on the bearing blocks 86 providing theparallel planar bearings 88 on which the bearing support reciprocates. Aservo motor (FIG. 1) 91, having a piston 92 reciprocably sealed incylinder 93 cast integrally with the motor cylindrical wall andconnected by a rod 94 to the bearing ring 82 ad justably reciprocatesthe bearing ring 61 to vary the displacement of the motor. The servomotor on the selective supply and exhaust of fluid to the opposedchambers thereof by a suitable control system including passages 95moves the center of the bearing ring transversely relative to the motoraxis or spider axis. While in the pump variable displacement means, thecenter of the bearing ring is moved on both sides of the pump axis toreverse the direction of pumping for forward and reverse drive, in themotor the center of the bearing ring is only varied to one side as motorreversal is not necessary. As pointed out above, the pumpdisplacement issimilarly varied by the structurally identical servomotor 65.

The motor pintle 77 has a first passage 96 and a second passage 97extending in an axial direction respectively to the first motoraxialpassage portion 98 and the second motor axial passage portion 99 inthe axial passage portion 46 of intermediate wall 42.

. The above first and second axial pump passage portions 68, 69 andfirst and second axial motor passage portions 96, 97 are respectivelyinterconnected by curved connecting passages extending alongside thepump-and motor cylindrical walls, as described below, all integrallycast with the intermediate wall. The first pump axial passage portion68-has an offset portion 101 extending to a circular first connectingpump passage portion 102 as shown in FIG. 1 formed by the addition of awall parallel to the motor cylindrical wall portion and a wall parallelto the intermediate wall portion which extends circularly a shortdistance along the perimeter of the motor cylindrical wall portion tothe nape 103 between the pump and motor cylindrical wall portions. Thefirst connecting pump passage portion is connected at nape 103 by ashort first axial transfer passage portion, or opening, 104 merelyextending across the thickness of the intermediate wall to the motorconnecting passage portion 105 which extends peripherally around thepump cylindrical Wall and has a portion parallel to it and a portionparallel to the intermediate wall portion. The passage 105 is connectedby a motor offset passage 106 to the first motor axial passage portion96.

The second pump axial passage 69 is directed directly to the second pumpconnecting passage portion 108 which extends oppositely to the firstpump connecting passage portion 102 circumferentially around the motorcylindrical wall across the pump portion of the intermediate wall andhas, as best shown in FIG. 2, a cylindrical portion 111 following themotor cylindrical wall portion and a flat portion 112 parallel to theintermediate wall portion curving withthe motor cylindrical wall. At theopposite nape 114, between the pump and motor cylindrical wall portions,there is a transfer passage portion 116 extending across theintermediate wall to the second motor connecting passage portion 117which extends around the pump cylindrical wall portion and across theintermediate wall and has,

like these other passages, walls parallel to the pump cylindrical wallportion and the intermediate wall and connects to the second motor axialpassage 97, as shown in FIG. 1.

l The hydrostatic transmission 11 has an enclosing circular mountingflange 1 18 which, as best shown in FIG. 1, extends around over half ofthe pump cylindrical wall 43 and less than half of the smaller diametermotor central axial passage portion with intermediate connectingportionsis secured. to the similarly shaped flange 30 on the engine block 14 bybolts 119.

The motor or hydrostatic transmission output shaft 121 extends through aseal and aperture 122 in the axial passage portion 46 of theintermediate wall member and through an aperture 124 in pintle 77 andhas a flange 126 secured by fasteners, i.e'., rivets 127, to the motorspider 78. The shaft at its opposite end is splined to an output gear131 rotatably mounted in spaced bearings 132, 132 supported in spacedwebs 133, 133,

the final drive housing portion 134 formed as an integral part of theblock portion 14 of the engine housing l8. The final drive shaft housingportion 134 is formed integrally with the upper portion of side wall 135of block 14 and its front portion provides the portion of flange 24aextending around the motor and projecting beyond block 14. The finaldrive shaft housing portion has a cross section shaped like flange 30 atits front end and an intermediate transverse web 133 and extends axiallyto the rear web or rear end wall 133'. The drive gear 131 is connectedby chain 136 having internal gear teeth to the spur ring gear 137mounted on the differential carrier 138. The differential carrier hasopposed symmetrical portions 139, 141 having radial flanges 142, 143 atone end in facing contacting relation. The ring gear 137 has a radialmounting flange 144. Screws 146 extend through gear flange 144 anddifferential flanges 142, 143 to secure the gear to the differentialcarrier and the differential flanges and portions together. Thedifferential carrier portions 139, 141 respectively have cylindricalsleeve portions 147, 148 having external bearing surfaces rotatablysupported by bearings 149 and 151 supported respectively in the bearingsupports consisting of a conventional semi-circular saddle 152, 153formed integrally with the differential housing flange portions 154, 156of the final drive housing 134 and a semi-circular cap member 157, 158bolted to the saddle. The carrier 138 has transverse pinion shaft 159clamped in radial bores 161 in carrier 138 formed by facingsemi-circular recesses in the flanges 142, 143. The pinion shaft hasbevel pinions 162 at each end rotatably mounted thereon and axiallyengaging bearing surfaces 163 on the internal surface of the sleeveportions 147, 148 of carrier 138. The carrier has in each oppositecylindrical sleeve portion an internal cylindrical bearing bore 164, 166rotatably receiving and supporting the cylindrical gear and universaljoint members 167, 168. Each member 167, 168 has on the end facing thebevel pinions, a bevel gear 169 meshing with both pinions and aninternal bearing bore 171 to receive the ball end 172 ofa swing axle173. Each bore 171 has diametrically opposed axial grooves 174 receivingdrive members 176 rotatably mounted on the cross pin member 177 fixed inthe ball end 172 of the swing axle. This is a constant velocityuniversal joint with the drive members having a spherical bearingsurface in bearing engagement with the flat sides of the recesses andthe pin having a spherical end in bearing engagement with the flat baseof the recess.

The universal joint slots 174 extend axially completely through the gearand universal joint members 167, 168 and partially interrupt the bevelgears 169 for ease of manufacture of this member. A thrust washer andsnap ring assembly 178 fixed in each internal bore 164, 166 of carrierportions 139, 141 to hold each member 167, 168 with its gear 169 inproper mesh with pinions 162..

If three pinions 180, FIG. 3, like the pair of pinions 162, or anotherodd number of pinions are used in an equal peripherally spacedarrangement in a carrier 179 like carrier 138, no pinion isopposite'another pinion so only one pinion can at any time engage arecess portion of an annular gear. This same effect can also be achievedby unequal peripheral pinion spacing of an odd or even number of pinionswhich also avoid having diametrically opposite pinions.

' The final drive assembly 12 has the above described final drive shafthousing portion 134 and a differential portion 181 having web walls 182,183 generally aligned with webs' 133, 133 perpendicular to the side ofthe engine block 14 and located on opposite sides of the chain 136 andhaving an outer wall 184. The final drive shaft portion is interruptedbetween web walls 182, 183 to provide a free space for the chain betweenthe block 14 and outer wall 184. The block 14 has a bottom flange 186extending around the base of the block and at each bottom edge of webwalls 182, 183 there are respectively flanges 154, 156 in the plane ofthe block base flange 186. The flanges 154, 156 are connected by axiallyextending flange 187 at the bottom end of outer wall 184. The oil pan'16 has a convenfrom one end said engine tional engine portion 188secured to engine block flange 186 and a side extension 189 providing adifferential portion secured to flanges 154, 156, 187 to enclose thelower portion of the engine and differential housings. Each side of thedifferential housing pan portion 189 has an aperture for a swing shaft173 and boot seal 191 between a swing shaft 173 and the differentialpan.

The operation and advantages of this power drive assembly are believedapparent from the above detailed description. The engine block hasrigidly combined therewith, preferably as a one piece casting, thehydrostatic support flange 30, the drive shaft housing 134 anddifferential housing 181 to mount the hydrostatic transmission with thepump on the engine axis, the motor on the drive shaft axis and bothspaced from the differential drive axis for a simple compact swing axlepower assembly. The hydrostatic transmission has a reduced offsetbetween the pump and motor axes and-a unitary rigid intermediate wallhousing, preferably a one piece casting, providing the pump and motorchambers and support for the pump and motoroperating mechanismandconnecting power circuit passages. The engine and pump axis, the motorand drive shaft axis and differential axes are located at the apexes ofa triangle and close together for this compact arrangement.

The above described preferred embodiments are illustrative of theinvention.

It is claimed:

1. In a power drive assembly; an engine having an engine housing and anoutput shaft extending centrally housing; said engine housing having atransmission mounting pad extending around said output shaft and adifferential housing portion projecting from the perimeter of saidenginehousing; a differential drive in said differential housing on an axisoffset and parallel to said output shaft, a hydrostatic transmissionhousing secured to said mounting pad having a main portion having anintermediate wall including a pump chamber with a pump therein coaxialwith and driven by said output shaft and including a motor chamber witha motor therein in fluid communication with said pump and having a motordriven shaft driven by said motor and located on an axis parallel to andspaced from said output shaft and said differential axis and driveconnected to said differential drive.

2. The invention defined in claim 1 and said engine housing having arigid block portion; said engine mounting pad being formed integrallywith said block portion and extending around both said output shaft andsaid driven shaft; said block portion having a base portion extending onone side to provide a portion of said differential housing portion; saidblock portion having an integral shaft support structure on said oneside above said base portion rotatably supporting said motor drivenshaft.

3. In a power drive assembly; an engine having an engine housing with apower portion, a driven shaft support portion on the upper part of oneside of the power portion and a differential drive portion on the lowerpart of said one side of the power portion; an engine output shaftdriven by said engine and rotatably mounted on one end of said powerportion; a hydrostatic transmission housing secured to said powerportion and having an intermediate wall with a pump chamber and motorpassages on the side facing said one end of said engine and pumppassages coaxial with said pump chamber and a motor chamber coaxial withsaid motor passages, both on the opposite side of said wall; pump meansmounted in said pump chamber coaxial with and drive connected to saidengine output shaft; motor means mounted in said motor chamber having acoaxial driven shaft driven by said motor means and rotatably mounted insaid driven shaft support portion in spaced parallel relation to saidengine shaft; said pump chamber and said motor chamber being in partialoverlapping relation with napes at the intersection of their perimetersto reduce the space between said engine shaft and driven shaft;connecting passage means extending from said pump passages along saidopposite side of said wall, across said wall at the napes between saidpump and motor chambers and along said one side of said wall to saidmotor passages; a differential drive rotatably mounted in saiddifferential drive portion on an axis spaced and parallel to both saidengine shaft and driven shaft and drive connected to said driven shaft.

4. The invention defined in claim 3 and connecting drive means driveconnecting said driven shaft to said differential drive and reinforcingwebs formed on said one side of said engine housing extending from saiddriven shaft supportportion to said differential drive portion tofurther support said last mentioned portions and forming at leastpartially enclosing said connecting drive means.

5. The invention defined in claim 3 and said pump chamber and passages,said motor chamber and passages and said connecting passage means ofsaid intermediate wall being formed integrally with said intermediatewall to rigidify and reinforce each other.

6. The invention defined in claim 5 and said pumps and motors beingradial pumps and motors having a central pintle fixed to said wallrespectively in said pump and motor chambers and each having a spiderrotatably mounted on said pintle and having spherical pistons andcylindrical cylinders on said pistons rotat ably mounted in the chamber.

1. In a power drive assembly; an engine having an engine housing and anoutput shaft extending centrally from one end said engine housing; saidengine housing having a transmission mounting pad extending around saidoutput shaft and a differential housing portion projecting from theperimeter of said engine housing; a differential drive in saiddifferential housing on an axis offset and parallel to said outputshaft, a hydrostatic transmission housing secured to said mounting padhaving a main portion having an intermediate wall including a pumpchamber with a pump therein coaxial with and driven by said output shaftand including a motor chamber with a motor therein in fluidcommunication with said pump and having a motor driven shaft driven bysaid motor and located on an axis parallel to and spaced from saidoutput shaft and said differential axis and drive connected to saiddifferential drive.
 2. The invention defined in claim 1 and said enginehousing having a rigid block portion; said engine mounting pad beingformed integrally with said block portion and extending around both saidoutput shaft and said driven shaft; said block portion having a baseportion extending on one side to provide a portion of said differentialhousing portion; said block portion having an integral shaft supportstructure on said one side above said base portion rotatably supportingsaid motor driven shaft.
 3. In a power drive assembly; an engine havingan engine housing with a power portion, a driven shaft support portionon the upper part of one side of the power portion and a differentialdrive portion on the lower part of said one side of the power portion;an engine output shaft driven by said engine and rotatably mounted onone end of said power portion; a hydrostatic transmission housingsecured to said power portion and having an intermediate wall with apump chamber and motor passages on the side facing said one end of saidengine and pump passages coaxial with said pump chamber and a motorchamber coaxial with said motor passages, both on the opposite side ofsaid wall; pump means mounted in said pump chamber coaxial with anddrive connected to said engine output shaft; motor means mounted in saidmotor chamber having a coaxial driven shaft driven by said motor meansand rotatably mounted in said driven shaft support portion in spacedparallel relation to said engine shaft; said pump chamber and said motorchamber being in partial overlapping relation with napes at theintersection of their perimeters to reduce the space between said engineshaft and driven shaft; connecting passage means extending from saidpump passages along said opposite side of said wall, across said wall atthe napes between said pump and motor chambers and along said one sideof said wall to said motor passages; a differential drive rotatablymounted in said differential drive portion on an axis spaced andparallel to both said engine shaft and driven shaft and drive connectedto said driven shaft.
 4. The invention defined in claim 3 and connectingdrive means drive connecting said driven shaft to said differentialdrive and reinforcing webs formed on said one side of said enginehousing extending from said driven shaft support portion to saiddifferential drive portion to further support said last mentionedportions and forming at least partially enclosing said connecting drivemeans.
 5. The invention defined in claim 3 and said pump chamber andpassages, said motor chamber and passages and said connecting passagemeans of said intermediate wall being formed integrally with saidintermediate wall to rigidify and reinforce each other.
 6. The inventiondefined in claim 5 and said pumps and motors being radial pumps andmotors having a central pintle fixed to said wall respectively in saidpump and motor chambers and each having a spider rotatably mounted onsaid pintle and having spherical pistons and cylindrical cylinders onsaid pistons rotatably mounted in the chamber.